This invention was developed at least partially with United States Government support under Grant No. AR 19098 from the National Institutes of Health and Grant No. AR39448 from the United States Public Health Service. The United States Government may have rights in this invention.
1. Field of the Invention
This invention relates to novel cosmetic and therapeutic methods for stimulating tissue growth and/or enhancing moisturization and lubrication in mammalian epithelium, such as skin and mucous membrane. The methods comprises providing to an individual a composition comprising at least one inhibitor of xcex2-glucosidase activity, a glycosphingolipid or the combination of a xcex2-glucosidase inhibitor with a glycosphingolipid.
2. Description of Related Art
Mammalian keratinizing epithelium, including the epidermis and various mucous membranes, provide protection against the invasion of microorganisms, physical trauma, toxic chemicals, and particularly loss of bodily fluids, i.e., a permeability barrier function. This barrier function derives from a combination of physical impenetrability, resilience, resistence to traumatic force, and its relative impermeability to water, attributable to a unique mixture of lipids within the outermost layer of skin, the stratum corneum.
Injuries to the skin barrier may occur from thermal burns, penetrating wounds, exposure to organic solvent, surfactants/detergents and a variety of irritating chemicals, and in a variety of blistering skin diseases. The repair of epidermal damage requires proliferation of basal cells to replace damaged cells. Because of limitations in the proliferative capacity of the epidermis the treatment of substantial damage to skin may require skin grafting for optimal recovery. Moreover the repair of skin damage becomes less than optimal with chronological or photoaging of skin, with immunosuppressed conditions, in patients with chronic diseases, such as cancer and as a consequence of therapy with some types of drugs. A further consequence of an insufficient proliferative capacity is an increased susceptibility to injuries with repetitive insults to the skin.
Among major cosmetic and therapeutic concerns are the age-and sun-associated changes that occur in the skin, such as wrinkling, thinning and increased susceptibility to injury. Thinning, brittle skin also results from abnormal hydration and alterations in hormonal levels resulting from the aging process. The stimulation of proliferation in skin and hair follicles has been attempted with steroidal compounds. (Palacios, H. J., U.S. Pat. No. 5,256,406) Retinoid-related compounds have also been used to treat sun damaged skin. (Kligman, A. M., U.S. Pat. No. 4,877,8050) However, previous methods have been only partially effective or subject to deleterious side effects.
Other epithelial tissues, such as mucous membranes, can also become compromised with aging, in individuals suffering from nutritional deficiency syndromes, and in post-menopausal hormone deficiency. These alterations can result in thin, dry, fragile, and/or atrophic mucous membrane. Ocular membranes especially exhibit reduced lubricating fluids with age and a variety of ophthalmic pathologies.
A major function particularly of both the epidermis and mucosal epithelia is to provide a barrier that prevents excessive loss of body fluids. This epithelial barrier is mediated by a system of multilayered membrane lipid-enriched bilayers that exist throughout the intercellular spaces of the stratum corneum in the epidermis and keratinizing mucous membranes. These multiple bilayers derive from lipids and proteins secreted from cells in the outer epidermis. These cells are in turn the products of the underlying proliferative basal cells.
The bilayers in the stratum corneum of epidermis are enriched in an approximately equimolar mixture of three major lipid species: ceramides (CER), free fatty acids, and cholesterol. The multilayered bilayers in keratinizing mucosal epithelia consist of approximately equimolar ratios of glucosylceramides (GlcCER), free fatty acids and cholesterol.
Of the three key lipids comprising the barrier, the ceramides comprise the greatest quantity (40-50%. by weight). Ceramides form the precursor/backbone of glucosylceramides (GlcCER), more complex glycosphingolipids (GSLs), and sphingomyelin (SM) (FIGS. 1+2).
Glycosphingolipids include gangliosides, globosides, and sulfatides. Gangliosides are glycosphingolipids containing at least one sialic acid (SA) bound to the ceramide core structure (FIG. 2). An example is GM1, a mono-sialic acid ganglioside. Sulfatides are glycosphingolipids with at least one sulfated oligosaccharide bound to the ceramide core structure. (Hakomori, S.-I. (1983), xe2x80x9cChemistry of Glycosphingolipidsxe2x80x9d, p. 1-165, in Sphingolipid Biochemistry J. N. Kanfu and S.-I. Hakomori, eds., Plenum Press, New York, N.Y.
In addition to their role in the epidermal permeability barrier, alterations in sphingolipid metabolism have been implicated in disease pathogenesis. In Gaucher""s disease, impaired glucocerebrosidase (GlcCER""ase) activity results in organomegaly. Tissue hyperplasia is associated with the accumulation of lipids, including GlcCER, within several tissues (e.g., liver, spleen) (Barranger, J. A., Ginns, E. I., Glucosylceramide Lipidoses: Gaucher Disease in Metabolic Basis of Inherited Disease. (1989), p. 1677, McGraw Hill Inc., New York, N.Y.)
The abnormalities in Gaucher""s disease point to disorder of GlcCER-CER metabolism as the cause of the tissue hyperplasia. A role for excess GlcCER is supported by the observation that injection of emulsified GlcCER into mice induces Gaucher-type hepatic hypertrophy. (S. C. Datta and N. S. Radin, Lipids 23:508-510 (1988)) Moreover, Gaucher""s disease is simulated with systemic administration of the specific inhibitor of GlcCER""ase, bromo-conduritol-B-epoxide to mice. Along with the elevations in cellular GlcCER content, hyperplasia of the brain and liver was observed (Hara, A., Radin, N. S., Biochim. Biophys. Acta 582:423-433 (1979). Furthermore, the epidermis in mucosal epithelia displays a preponderance of GlcCER and depletion of CER in association with depletion of xcex2-glucosidase activity (Squier, C. A., et al. Arch. Oral Biol. 31:741-747 (1986).
Finally exposure of cultured MDCK cells (kidney) to conduritol-B-epoxide results in a time-dependent accumulation of GlcCER with a parallel increase in cellular proliferation (Shayman, J. A. et al., J. Biol. Chem. 266:22968-22978 (1991)). Thus increased GlcCER levels have been associated with pathological organomegaly in susceptible organs, with proliferation in cultured cells and the normal formation of mucosal surfaces. However epidermal structures are typically not associated with GlcCER-sensitive disease states, such as Gaucher""s disease.
Accordingly there is still a need for a safe and effective method that will both enhance epithelial growth and restore a smooth, pliant, flexible, well-lubricated surface to the stratum corneum and mucous membranes, includig the conjuctivae of the eye.
The invention herein encompasses a method effective to stimulate cell proliferation and enhance epithelial moisturization and lubrication of mammalian subject or mammalian cells wherein a composition comprising one or more inhibitors of xcex2-glucosidase activity, a glycosphingolipid or a combination of one or more inhibitors of xcex2-glucosidase and a glycosphingolipid is administered to the subject or cell.
The invention further includes a method effective to enhance epithelial moisturization and lubrication and separately encompasses a method effective to stimulate cell proliferation wherein a composition comprising one or more inhibitors of xcex2-glucosidase, a glycosphingolipidor a combination of one or more inhibitors of xcex2-glucosidase and a glycosphingolipid is administered to a subject.
Also included in this invention is a composition comprising one or more inhibitors of xcex2-glucosidase and a glycosphingolipid useful to stimulate cell proliferation and enhance tissue moisturization and lubrication.
The above features and advantages of this invention will be more fully understood by reference to the following detailed description and the drawings.